Method for zone hardening



Aug. 18, 1942. F. s. DENNEEN ETAL METHOD FOR ZONE HARDENINGl original Filed Dec. :51. 1935 INVENTO Patented Aug'. 18,1942

METHOD Fon zoNE HARDENING Francis S. Denneen, Cleveland, and William C. Dunn, Shaker Heights, Ohio, assignors to The Ohio Crankshaft Co., Cleveland, Ohio, a corporation of Ohio Original application December 31, 1935, Serial No.

1940, Serial No. 326,946

' (C1. 14a-1o) Claims.

Thepresent invention, relating as indicated to a method for zone hardening, is a division of our co-pending application No. 56,870, filed December 31, 1935, for Apparatus for zone hardening.

We have found that utilization of the various apparatuses and'V methods for zone hardening heretofore made available are somewhat unsatisfactoryA particularly when such zonestermil The primary object of this invention has beento provide a method for uniformly hardening a Divided and this application March 30,

member 29 is adapted to rotate about hinge pinir 32 which iscarried in the stationary hinge member 33.` Extension 26 and stationary hinge member 33 are attached to stationary bus bars 35 and 36 respectively by bolts 31 and 38, these bus bars being attachedpreferably by fusion to the ends of the single coil secondary 39 of the transformer. The primary turns indicated by the fragment 39 are insulated from each other and from the secondary by suitable means. To relieve the bus bars 35 and 36 from strains which would occur in the vmanipulation of the inductors-both pins 28 and 32 have their ends supzone the neighboring elements vof which are magnetically permeable. A further object of this invention has been to provide apparatus for practicing a method of the character described which is capable of being accurately andquickly set-up.

To the accomplishment of the foregoing and related ends, said invention, then,` consists of the means hereinafter described and particularly pointed out in the claims; the annexed drawing and the ,following description setting forth in detail one method constituting, however, but one of various applications of the principle of our invention.

In said annexed drawing:

Fig. 1 is an'end view partially fragmentary and partially sectional of apparatus forpracticing this invention; and

Fig. 2 is a partially fragmentary section taken on the line 2--2 of Fig. 1.

Figs. 1 and 2 show a specific application of this invention to a crankshaft crankpin which is to be hardened. The crankshaft, which is fragmentarily shown, comprises main bearings I0, pin II and interconnecting, cheeks I2. It is to be understood that crankshaft is used herein by way of illustration and not limitation. The inductor members I 4 and I5 have jackets 'I1 and I8 attached by screws 20 and 2l. Suitable insulation gaskets 23 of rubber or other resilient material serve as means for preventing loss of the quenching medium and to fconflne the flow of current to the inductor members adjacent to the pin. lThe lower inductor member I5 is attached by means of bolt 25to the extension 26 which is supported by the pin 28 and the upper inductor member I4 is attached to the hinge ported in the frame carrying the coils and other related parts, and which is not shown.

In applying the inductor members to the crankshaft bearing or pin II, an insulating space between these inductors and their supports is provided. This space is usually maintained at a minimum to prevent losses and ordinaril is of the o rder of one sixteenth of an inch. e outer ends 4I and 42 of the inductor men fers are brought into rm conducting contact to implete the Icircuit around theshaft.` Usually the voltage is low and the current density is very high at this contact so that very slight difference in the contact resistance at different points in the contacting area will cause serious variation in the current density from one side to the other of the inductor members This causes corresponding and objectionable variation in the rate of heating in different sections in the zone to be heated. To insure uniformly high conducting contact, we usually attach silver contact strips 44 and 45 to the said outer ends and provide a C clamp 46 for clamping the same together. For

' some purposes, it is satisfactory to omit these member 29 byl meansof bolts 30. The vhinge 55L depth of hardened zone in the center section of the width o'f the bearing. To correct this condition so as to make the 4depth of the hardened zone approximately uniform across the width of the bearing, we frequently recess the face of the inductor member bringing it further away from the surfaceto be heated at the place where a parallel inductor member would tend to create excessive or objectionable depth in the hardened zone. This recessing is indicated at 41 in Fig. 2 and provides a surface zone of substantially uniform depth when other related conditions are favorable. Frequently, however, neighboring elements may disturb the desired distribution of the magnetic flux such, for instance, as the arms or cheeks I2 of the crankshaft. To compensate for the presence of these elements the pin Il is placed in an eccentric position relative to the inductors so that the least clearance between the inductor members and shaft is between the arms or cheeks. For most satisfactory results, it has been found that for journals having a diameter of approximately two and one-half inches, the clearance at 48 should be of the order of .080 of an inch, at 49 it should be .040 and at 50 and 5| .060. Small cylindrical spacers made of lava or other insulating material as shown at 53 are usually inserted to insure the desired spacing.

Other forms may be employed embodying the features of our invention instead of the one here explained, change being made in the form or construction, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed, whether produced by our preferred method or by others embodying steps` equivalent tothose stated in the following claims.

We therefore particularly point out and distinctly claim as our invention:

1. In a method of equalizing heating of a periodically varying flux field in a surfacezone of a-journal, the journal having a substantially radially extending arm in proximity with one end thereof, the steps comprising placing an inductor in embracing relation with the journal and in proximity with the arm, the inductor being spaced from the surface zone of the journal and in the proximate arm, the current being induced in the arm effecting a shifting of the ux field in the journal to reduce heating in the arm adjacent side of the journal, and reducing the space between the inductor and the journal on the said arm adjacent side of the journal by shifting the inductor relatively to the journal suiciently to substantially overcome Vthe shifting of the' flux field in the journal to substantially equalize heating in the diametrically opposite sides of said journal. y

2. In a method of equalizing heating of a periodically varying flux field 'in a surface zone of a journal, the journal having a substantially radially extending arm in proximity with one end thereof, the steps comprising placing an inductor v'in embracing relation with the journal and in proximity with the arm, the inductor being spaced from .the surface zone of the journal and from the arm, the inductor being shiftable transversely of the journal so that the space between the inductor and journal onthe arm adjacent side of the journal can be made substantially less induced in the arm effecting a shifting of the ux eld in the journal toreduce heating in the arm adjacent side of the journal, and reducing the space between the inductor and the journal on the said arm adjacent side of the journal by shifting the inductor relatively to the journal so that the said space between the inductor and the journal on the arm adjacent side of the journal will be substantially one half of the space between the inductor and the journal on the side of the journal opposite to said arm to substantially equalize heating in the diametrically opposite sides of the journal.

3. In a method of equalizing heating of a periodically varying iiux field in a surface zone of a journal, the journal having a substantially radially extending arm in proximity with one end thereof, the steps comprising placing an inductor in embracing relation with the journal and in proximity with the arm, the inductor being spaced from the surface zone of the journal and from the arm, the inductor being shiftable transversely of the journal so that the space between the inductor and the journal on the arm adjacent side of the journal can be made substantially less than the space between the inductor and the y journal on a diametrically opposite side of the that the said space between the inductor and the y journal on the arm adjacent side of the journal will beof the order of three sixty-fourths of aninch and the space betwe'en the inductor and journal on the side of `the journal opposite to said arm will be of the order of live sixty-fourths of an inch to substantially equalize heating in the diametrically opposite sides of the journal.

4. In a method of equalizing heating of a periodically varying iiux field in a surface zone of an article, the article having a projecting member adjacent to the surface zone, the steps comprising placing an inductor in substantially closely spaced relation with` the surface zone to induce heating current in the zone, and then shiftlng the inductor to provide a non-uniform spacing of the inductor and thearticle to eiIect a uniform heating of the surface zone. y

5. In amethod of equalizing heating Aof a periodically varying flux field in a surface zone of an article, the article having a projecting member adjacent to the surface zone, the steps comprising providing an inductor adapted to encircle a part of the article, the inductor having spaced terminals attached thereto, bringing the inductor into encircling relationship with the article, locating the space between the terminals of the inductor at a point substantially on an opposite sideof the article to the aforesaid projecting member, then shifting 4the inductor to bring a part of the inductor' into closer relation with a side of the article adjacent to the projection and to bring another part ofthe inductor, into more distant relationl with an opposite side oi.' the article to substantially equalize heating in the said sides of the article, and supplying inducing current to the terminals of the inductor.

FRANCIS s. DENNEEN.l

WrLLIAM C. DUNN. 

